Chucks of the type to which this invention is directed have a number of internal moving parts which serve to open and close the jaws. The operation of these parts is most important to assure that there is a positive clamping of the workpiece when the jaws are closed and further that each of the jaws applies equal pressure against the workpiece to prevent distortion and possible eccentric location of the workpiece. At the speeds at which many chucks are used in modern manufacturing processes, even slight eccentricity can be quite serious from both a safety point of view and from the point of view of wear and early failure of the equipment. It also is likely to cause improper machining requiring rejection of the workpiece. In this connection, it is important that the moving parts which control the movement of the jaws be properly lubricated. It is necessary to assure adequate lubrication of each bearing point between the parts. This is necessary both to assure proper actuation and to reduce wear.
In doing this there will be a certain amount of lubricant which becomes discharged from the moving parts into the interior of the chuck body and collects within the body. In prior constructions, not only has it not been possible to assure lubrication of all of the critical points in the chuck actuating system, there has also been the problem of the excess lubricant collecting in certain areas of the chuck in such amounts that significant weight imbalance is generated by the lubricant's presence. Further, this accumulation of lubricant will occur at the outermost portion of the interior of the chuck because of the centrifugal forces acting upon it during chuck operation. This situation creates undesirable and, in some cases, unacceptable eccentricity of the chuck.